Amorphous magnetic alloy materials have been extensively studied for commercialization because of their excellent electromagnetic properties. Particularly, Co-Fe-Si-B type amorphous alloys of specific compositions can achieve very low magnetostriction, and are very much expected to find applications as materials for magnetic heads, magnetic sensors, etc. Attempts have been actively made to improve their electromagnetic properties such as magnetic permeability and magnetic flux density by adding various elements to the Co-Fe-Si-B type amorphous alloys. For example, there are amorphous alloys in ribbon form having increased magnetic permeability as a result of adding suitable amounts of elements such as Nb, Ni, V, Ta, Ti, Zr, Cr, Mo, and W, as described, e.g., in Japanese Patent Application (OPI) Nos. 72715/79, 89918/79, 107826/79, 107827/79, 13137/82, and 31053/83 (The term "OPI" as used herein refers to a "published unexamined Japanese patent application.").
Japanese Patent Application (OPI) No. 79052/82 (corresponding to U.S. Pat. No. 4,527,614 and European Patent 50,479) discloses high-quality Co-type fine amorphous metallic wires circular in cross section which have a very uniform shape with a circularity of at least 90% and a diameter variation of not more than 4%.
Amorphous metallic ribbons produced by the one roll method by the present inventors from conventional Co-type amorphous metals, for example, an alloy having the composition (Co.sub.0.92 Fe.sub.0.06 Cr.sub.0.02).sub.75 Si.sub.10 B.sub.15 or an alloy having the composition (Co.sub.0.92 Fe.sub.0.06 Ta.sub.0.02).sub.75 Si.sub.10 B.sub.15 described in Japanese Patent Application (OPI) No. 107827/79, an alloy having the composition (Co.sub.0.91 Fe.sub.0.06 -Nb.sub.0.03).sub.77 Si.sub.15 B.sub.8 described in Japanese Patent Application (OPI) No. 31053/83, and an alloy having the composition (Co.sub.0.92 Fe.sub.0.06 Ni.sub.0.02).sub.78 Si.sub.13 B.sub.9 or an alloy having the composition (Co.sub.0.91 Fe.sub.0.06 Mo.sub.0.03).sub.78 Si.sub.13 B.sub.9 described in Japanese Patent Application (OPI) No. 13137/82 had low magnetostriction, high magnetic permeability, and high saturation magnetic flux density, but when a bias magnetic field was applied thereto, the magnetic permeability decreased abruptly. Specifically, when amorphous metallic ribbons having a thickness of about from 5 to 100 microns (.mu.m) and a width of from 2 to 100 mm were produced by jetting a molten mass of a Co-Fe-Cr-Si-B type alloy, a Co-Fe-Mo-Si-B type alloy, or a Co-Fe-Ni-Si-B type alloy onto a rotating cooling roll made of a material having high thermal conductivity such as a copper, these ribbons markedly decreased in magnetic permeability under the influence of a bias magnetic field.
Such ribbon which decreases in magnetic permeability in a bias magnetic field cannot be used in practical applications because when it is applied, for example, to a coordinates reading device, signals obtained become abruptly weak due to even a slight bias magnetic field, for example by the influence of the earth's magnetism owing to the differences in the directions of east, west, south, and north, or by the influence of a magnetized body near the measuring instrument.
The Co-type fine amorphous metallic wires described in Japanese Patent Application (OPI) No. 79052/82 have superior electromagnetic properties and corrosion resistance, but their magnetic permeability decreases under the influence of a bias magnetic field. Hence, they are not fully acceptable as a material for a coordinates reading device, for example.